-----Original Message----- From: alsa-devel-bounces@alsa-project.org [mailto:alsa-devel- bounces@alsa-project.org] On Behalf Of Sascha Hauer Sent: Thursday, November 10, 2011 6:26 PM To: Dong Aisheng-B29396 Cc: alsa-devel@alsa-project.org; broonie@opensource.wolfsonmicro.com; w.sang@pengutronix.de; Guo Shawn-R65073; u.kleine-koenig@pengutronix.de; lrg@ti.com; linux-arm-kernel@lists.infradead.org Subject: Re: [alsa-devel] [PATCH v4 2/3] ARM: mx28evk: add platform data for saif
On Thu, Nov 10, 2011 at 09:23:18AM +0000, Dong Aisheng-B29396 wrote:
+static const struct mxs_saif_platform_data
mx28evk_mxs_saif_pdata __initconst = {- .init = mx28evk_mxs_saif_pinit,
- .get_master_id = mxs_get_saif_clk_master_id,
This looks *very* suspicious. .init sets the mux register and .get_master_id reads the very same information back. Why not simply put a bool is_master into platform data?
Originally it's used to avoid introduce a global variable to save clkmux Since we can directly read it from register.
If put a bool is_master into pdata, we are assuming there are only two saif Instances. As I was suggested by Wolfram before that how about if there are more than two saifs in the future SoCs?
I don't understand. A is_master variable in platform_data does not make any assumption about the number of interfaces in the system.
I was thinking that you may mean we can assume saif1 is master if saif0_pdate.is_master is false. So here we assume there two interfaces and the other is master. Sorry if I mislead your meaning.
So the original saif driver design is following this rule that it only needs to know its master id.
If that's the design then put the master id into platform_data. This information is purely static and the board knows it. No need to put a function in platform_data. Something like this: struct saif_pdata { bool master_mode; /* if true use master mode */ int master_id; /* id of the master if in slave mode */ };
Yes, you're right. I will try that. Thanks for the suggestion.
If we decide to change here, I may also have a lot to change in saif
driver.
Some lines in the probe code, not more.
Sascha
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Regards Dong Aisheng